155 lines · c
1// SPDX-License-Identifier: GPL-2.0-only2/*3 * SMI methods for use with dell-smbios4 *5 * Copyright (c) Red Hat <mjg@redhat.com>6 * Copyright (c) 2014 Gabriele Mazzotta <gabriele.mzt@gmail.com>7 * Copyright (c) 2014 Pali Rohár <pali@kernel.org>8 * Copyright (c) 2017 Dell Inc.9 */10#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt11 12#include <linux/dmi.h>13#include <linux/gfp.h>14#include <linux/io.h>15#include <linux/module.h>16#include <linux/mutex.h>17#include <linux/platform_device.h>18#include "dcdbas.h"19#include "dell-smbios.h"20 21static int da_command_address;22static int da_command_code;23static struct smi_buffer smi_buf;24static struct calling_interface_buffer *buffer;25static struct platform_device *platform_device;26static DEFINE_MUTEX(smm_mutex);27 28static void parse_da_table(const struct dmi_header *dm)29{30 struct calling_interface_structure *table =31 container_of(dm, struct calling_interface_structure, header);32 33 /* 4 bytes of table header, plus 7 bytes of Dell header, plus at least34 * 6 bytes of entry35 */36 if (dm->length < 17)37 return;38 39 da_command_address = table->cmdIOAddress;40 da_command_code = table->cmdIOCode;41}42 43static void find_cmd_address(const struct dmi_header *dm, void *dummy)44{45 switch (dm->type) {46 case 0xda: /* Calling interface */47 parse_da_table(dm);48 break;49 }50}51 52static int dell_smbios_smm_call(struct calling_interface_buffer *input)53{54 struct smi_cmd command;55 size_t size;56 57 size = sizeof(struct calling_interface_buffer);58 command.magic = SMI_CMD_MAGIC;59 command.command_address = da_command_address;60 command.command_code = da_command_code;61 command.ebx = smi_buf.dma;62 command.ecx = 0x42534931;63 64 mutex_lock(&smm_mutex);65 memcpy(buffer, input, size);66 dcdbas_smi_request(&command);67 memcpy(input, buffer, size);68 mutex_unlock(&smm_mutex);69 return 0;70}71 72/* When enabled this indicates that SMM won't work */73static bool test_wsmt_enabled(void)74{75 struct calling_interface_token *wsmt;76 77 /* if token doesn't exist, SMM will work */78 wsmt = dell_smbios_find_token(WSMT_EN_TOKEN);79 if (!wsmt)80 return false;81 82 /* If token exists, try to access over SMM but set a dummy return.83 * - If WSMT disabled it will be overwritten by SMM84 * - If WSMT enabled then dummy value will remain85 */86 buffer->cmd_class = CLASS_TOKEN_READ;87 buffer->cmd_select = SELECT_TOKEN_STD;88 memset(buffer, 0, sizeof(struct calling_interface_buffer));89 buffer->input[0] = wsmt->location;90 buffer->output[0] = 99;91 dell_smbios_smm_call(buffer);92 if (buffer->output[0] == 99)93 return true;94 95 return false;96}97 98int init_dell_smbios_smm(void)99{100 int ret;101 /*102 * Allocate buffer below 4GB for SMI data--only 32-bit physical addr103 * is passed to SMI handler.104 */105 ret = dcdbas_smi_alloc(&smi_buf, PAGE_SIZE);106 if (ret)107 return ret;108 buffer = (void *)smi_buf.virt;109 110 dmi_walk(find_cmd_address, NULL);111 112 if (test_wsmt_enabled()) {113 pr_debug("Disabling due to WSMT enabled\n");114 ret = -ENODEV;115 goto fail_wsmt;116 }117 118 platform_device = platform_device_alloc("dell-smbios", 1);119 if (!platform_device) {120 ret = -ENOMEM;121 goto fail_platform_device_alloc;122 }123 124 ret = platform_device_add(platform_device);125 if (ret)126 goto fail_platform_device_add;127 128 ret = dell_smbios_register_device(&platform_device->dev,129 &dell_smbios_smm_call);130 if (ret)131 goto fail_register;132 133 return 0;134 135fail_register:136 platform_device_del(platform_device);137 138fail_platform_device_add:139 platform_device_put(platform_device);140 141fail_wsmt:142fail_platform_device_alloc:143 dcdbas_smi_free(&smi_buf);144 return ret;145}146 147void exit_dell_smbios_smm(void)148{149 if (platform_device) {150 dell_smbios_unregister_device(&platform_device->dev);151 platform_device_unregister(platform_device);152 dcdbas_smi_free(&smi_buf);153 }154}155